The dispersion of pigments in liquid ink systems is commonly achieved in an initial grinding step in the presence of a dispersing resin, such as nitrocellulose. The pigment dispersion is then added to a “let-down” resin, such as a polyamide, polyester, vinyl, acrylic, or polyurethane resin, depending on the requirement of a given substance.
Not all dispersants are compatible with all common let-down resins, e.g., nitrocellulose in polyamides of high molecular weight and vinyl resins. This requires the preparation and storage of several pigment dispersions, each specific for one or more let-down resins. A “universal” pigment dispersant would obviate this requirement.
In addition, adhesion promoting substances also called wetting agents generally consist of surface-active agents that function primarily by reducing the surface tension of liquids, i.e., let-down resins to facilitate the wetting of that function primarily by reducing the surface tension of liquids, i.e., let-down resins to facilitate the wetting of solids, i.e., pigments. In the past, their use had to be carefully controlled as each pigment/vehicle combination would behave differently and require changes in formulations to give stable systems (Printing Ink Handbook, 1988, p. 22).
The use of aryl sulfonamides in the prior art has been primarily as plasticizers, i.e., as liquid or solid additives to resin systems to impart flexibility in coatings (D. Aelony, Ind. Eng. Chem. 46:587 (1954)). Polymers derived from diamines and aryl disulfonyl chlorides have been prepared, generally via interfacial polymerization, for use in heat-resistant coatings and as blowing agents. Their use as adhesion promoting and/or pigment dispersing agents has not been reported.